Means for transmitting electric currents with increased energy.



'PA ENTED MAR. 17, 1908.

' J. AQSTRATTQN.

MEANS FOR TRANSMiTT'ING ELECTRIC CURRENTS WITH INCREASED ENERGY L APPLICATION IILED JULY 13.1906.

' WITNESSES JUL I AN A. STRATTON, OF GHECAGO, .ILLZNOKS.

ANS FOR TRANSMITTING ELECTRIC CURRENTB WITH INGREASED ENERGY.

Specification of Letters Patent.

PatentedMarch 17, was.

Application filed July 13, 1906. "Serial No. 326,136.

To all whom it may concern:

Be it known that I, JULIAN A. STRATTON, a citizen olthe United States, residing at ("hicago, in the county oi (look and State of Illinois, have invented certain newand use' ful Improvements in Means for Transmitting and the. like. used in two-way transmission.

" motive. forces are set up in them which vary remaining constant.

Electric Currents with Increased Energy, of which the following is a specification, reference being" had to the accompanying drawings.

My invention relates to improvements in means for transmitting electric waves orun dulntions, giving to them increased energy in their propagation; and as hereinafter set forth, my invention is shown and described. as embodied in what are called telephone re waters. lt will, however, be obvious to all skilled in this art that the particular use to which the invention is put may be varied through a wide. range.

in the following description and claims,

the terms, primary and secondary refer,'respectivcly, to the parts of the device which receive and which transmit the currents. whether such parts be connected directly to the lines or indirectly thereto through intermediate devices. It is my intention to cover in the following description only the essential features of my new device and certain modifications thereof, but to omit description of parts which are depend ent upon the mode of connection of my new device in the circuit, such as induction coils in the electrodynamicor dynamo type oi telephone repeaters, the essential features may be described follows: The voice currents (which are the currents to be reproduced or transmitted with an increase of energy or intensity) pass through suitable primary windings, which correspond to the field windings of a generator, and by their passage there set up a varying magnetic field the variations of which correspond to the variations of the currents which produce it. Through the varying magnetic held'so established, there is moved a conductor or combination oi conductors from which the currents generated by such motion are led to the secondary or transn'iitting circuit. By virtue of the motion of the said conductors through the varying magnetic field, electroas' the. field they are cutting varies from in stunt to instant, the s eed of the conduvtors herefore, the currents,

doctors through the magnetic fie d. 'Vario 's forms of this type ofre cater "have been devised, using the homopo ar type and' the' commutator ty e of electric motors or generators, of whic' those designed particularly for electrical smoothness of operation are selected in orderto revent disturbances due to irregularities in the generation of the BBC? ondary elec'tro motive forces.

Ann increase of ener y of the electrical vibrations is theoreticall T obtainable by this means alone; but it is found in ract ce that it is diiiicult to obtain any so stan'tial increase of such energy without resorting to the use of excessive speeds for the moving conductors. For example, using a repeater of this (dynamo) type, running at high speed,

it has beenfound by me that the electrical energy delivered from the moving conductors oi the secondary was ap roximately eight times that supplied to t 6 primary windings, when a constant direct current was used as the exciting current. Using the same repeater and running it at the same s eed but with telephonic voice currents as tiie field exciting current, I found that the energy of the electrical vibrations delivere-d from the secondary or transmitting circuit was even less than that available in the primary side, the comparison being made by a telephone receiver. This result is due to the fact that the telephonic voice currents are pulsating or alternating in 'char actor and of high frequency and are, therefore, opposed in their passage through the primary. windings by the inductive impedance of those. windings; and this inductive impedance is of such a high value that the strength of the magnetic fields established by netic field at an extremely high s eed, or must be of very great length. In t e latter case the increase of resistance consumes a ,large part of the energy generated. Furthermore, the higher harmonics of the voice currents are more effectually-suppressedthan those of low frequency, which 15 a disadvantage as the higher harmonics naturally suffer the greatest loss in transmission.

The object of my invention is to provide a repeater in which the eiiects of the inductive impedance above referred to will be reduced to a minimum and in which the higher harmonics will not only be allowed to pass'but will also be repeated, reproduced or transmitted with greatly increased energy. further object of my invention is to provide a re eater in which a wide range of selection of tie parts of the telephonic scale to be transmitted (or of waves of widely different length) may be made.

Another object of my invention is to provide a repeater inwhich a maximum efficiency of transmission will be attained.

In carrying out my invention, I use a rimar y or field winding having in series wit it a. condenser suitably proportioned as described below, the combined parts being connected to the line in the ordinary manner. The values of the capacity of the condenser and the coeilicient of self-induction of the primary winding are so chosen that a condition of resonance exists for currents of a certain fre uency, which may be termed the critical requency and whichhas a definite relation to the frequency of the voice currents composing the telephonic scale. Currents, alternating or pulsating, of the chosen frequency, pass through the primary windings practically as freely as would direct current through a similar winding without the condenser, and they establish a field of such strength that a large increase of energy for currents of the critical frcquencyis obtained in the moving secondary conductors cutting that field. From this it follows that the function of the resonant circuit is to allow the passage through the winding of sufficient current to establish the proper strength of variable magnetic ficld.-

I or currents above and below the critical frequency, the nature of the effect is the same, although in a lesser degree, and decreases as the dill'erence in frequency becomes greater. The critical frequent: is chosen with regard to the frequencies 0 the voice currents of the telephonic scale, depending upon the results which it is desired to obtain. it may be taken in the upper part of the scale, thus causing the repeater to reinforce most strongly the vibrations of high pitch which lend distinctncss to telephonic conversation; or it may be taken in the lower part of the scale to magnify ,tion, I have describer a sin the loudness of the speech reproduction; or it may be taken at any point intermediate these extremes. v a

To make 'clear the rinciple of my invenmary circuit; butin its app ication prefer to use a plurality of such resonant windings or circuits, to fre uencies taken at suitable intervals along tlie telephonic scale. By these means the. voice currents are greatly magnif ed throughout the whole scale by increasing the strength of the variable magnetic field which acts upon the secondary element, the effect of the different primary windings merging into each other at intermediate oints. Any part of the scale may, neverthe ess, bemore strongly reinforced than the rest, if desired. For example, if it is desired that the frequencies of a certain order should predominate, the resonant windings corresponding to that part of the scale may be tuned to frequencies at relatively closer intervals, or may be arranged to have a relativel larger number of turns.- While the indivi ual prima resonant circuits are preferably connects to the line in parallel, the essential feature of the arrangement of parts is that a resonant path be provided for each chosenfrequency. In some cases itmay be desirable to provide for frequencies above or below the telephonic scale. Such a provision may be made in the same manner as for frequencies within the scale. The frequency. intervals may be taken 'equally,or in any other desired way, the number of possible intervals depending u on the mechanical construction chiefly. T e closer the intervals are taken, the more uniform is the reinforcement; but a la.

number of intervals is not required to gi e satisfactory results. This system ofresonant primary windings ma be applied to any telephonic repeater emp oying a variable magnetic field established or controlled by the currents which it is desired to reinforce. The function of such windings remains the same as just described in connection with the elcctrodynamic 'or dynamo type of repeater namely, the increasing in intensity of the variations of field strength obtainable from a given available amount of electrical energ although the function which such a varia )le field serves in the operation of the repeater may be different in the different types. Thus, in a repeater using a variable magnetic field to actuate a magnetic diale resonant pri-.

the different circuits being tuned phra'gm, or armature, which operates a varithe is the establishing of a variable. magnetic 65 fundamental vibrations, which determine l-iield by the telephonic cul'rcpts, whether form is used.

available for transmission, if the voltage,

such field exists alone or in connection with other magnetic fields. However, I prefer to use the dynamo type of repeater, because of the positive nature of its operation and the absence of microphonic contacts and diaphra'gms. In the dynamo type of repeater, either the commutator type or the unipolar type of machine may be used; and either the field structure or the secondary conductors, or both of them, may be made the moving element. or elements. The energy used to provide for the relative motion should be-observed, in order to obtain the The parts of the magnetic cir-. cuit subjected to alternating or to fluctuating best results:

magnetic fields should be laminated or stranded. Further, it is desirable to use a small amount of iron in that part of the circuit composing the path of the variable magnetic field set up by the voice currents. Anyperiodica'lly recurring irregularity in the generation of the secondary currents will cause objectionable disturbances in the secondary circuit. These disturbances are more liable to occur, whcnthe armature is of the commutating type, than when the unipolar o avoid this, smooth core armatures should be used carrying a large 'number of armature coils and provided with a large number of commutator segments, in those cases in which the commutating type of armature is used; the brushes should be wide with respect to the commutator segments, or a plurality ofbrushcs should be used; and the pole pieces should be formed in such a way that the conductors enter and leave the variable magneticfield graduallyl Although there is an increase in the electrical energy delivered from the secondary of the repeater over that received in the primary, this increase in the energy will not be variations are too small. Consequently, it. is found desirable in some cases to step up these voltage variations before rc-transi-nissionand this is done by means of an induction coil, the use of which is particularly dcsirable Where the unipolanform of generator is emplo ed in the repeater. Even in the case of t e commutator type of repeater, I consider. it more desirable to obtain a high Value of voltage variation by means of stepup devices, than to make the armature conductors of great length. An induction coil with a suitable ratio oftransformation may be used, its primary being connected to the repeater and its secondary to the/line.

It will be understood that my invention is not limited in its application to the reinforcement of currents transmitting speech, the.

particular use to which the currents reinforced are put, or the particular mode of generation of the primary pulsating or alter nating currents, not having any bearing upon the scope of my invention.

My invention may be embodied in a rcpeatcr in any electrical systcn'i in which the frequency of the currents employed are of the orderof those used in transmitting speech or are such as to render the inductive impcdance of ordinary primary windings objectionable, as, for example, in the electrical transmission of music.

In the drawings illustrating thcprinciple of my invention and the best mode. now known to me of applying that principle, Figure 1 is a diagrammatic representation of a series of resonant circuits tuned to given frequencies; Fig. 2 shows diagrammatically a repeater of the dynamo type the variable field of which is generated by currents flowing in such resonant circuits; Fig. 3 is a view similar to that of Fig. 2 but showing a repeater of the variable resistance type instead of one of the dynamo type; and Fig. 4 illustrates the" mode of arranging the primary windings to link difi'erent magnetic circuits.

In series with the primary windings o, b and c are respectively, the condensers (I, e

and f eac of which condensers is so proportioned with regard to its associated wmding that a condition oi resonance exists in each of the three circuits for currents of a given frequency traversing that circuit, each chosen frequency being properly related to the scale of l'rcipicncics ol' the currcnts which the re pea-tor is intended to reinforce in the manner heretofore described. Under the action of the pulsating or alternating currents from a transmitter r in a circuit of which the terminals are the common terminals {1, h of the three resonant circuits, the primary windings (r, I) and c establish variable nmgnetic fields which serve in the operation of the rebcatcr in the manner above described. The object of the resonant primary circuits is to provide certain paths free from inductive impedance for currents ol"ccrtain frequencies to one of which each circuit is tuned, as before stated, and to eliminate to a less (or partial) degree the ei'l'cct of such impedance on currents of frequencies intermediate or between those selected (the critical frequencies of the respective circuits). In this way more powerful magnetic iiclds are obtained than could be obtaincc ithout the use of such resonant circuits, the number of which may be greater or less than the number shown in the drawings depending upon the closeness with which it is desired to cover the range of frequencies in question. The windings a, b and 0 may link the same magnetic circuit or they may link circuits wholly or partially distinct. In the first case the magnetic fields produced by the several windings are combined throughout the entire magnetic circuit, while in the second case the magnetic field setup by each individual winding is established in a magnetic circuit which, if not wholly, is at least partially'separate from the magnetic fields set up by the others.

The magnetic fields established through the different magnetic circuits are combined at the point where they are utilized, as at the armature 'of the secondary in Fig. 2, where the repeater is of the dynamo type, or at the diaphragm where the repeater is of the variable resistance type, as shown in Fig. 3. The object of ti'ris latter arrangement is, to

'the greater part of the available primary:

minimize, if not-toeliminate, the inductive effect upon one another of the windings devoted to the different critical frequencies of the several tuned circuits, in order to increase the total number of effective ampare-turns producing the variable magnetic eld, the strength of which is thereby increased. In explanation of this result it may be stated that, although the primary circuit resonant to a particular frequency receives energ of that frequency, it is still desirable to uti ize as much as possible of the remainder of such energy by means of-the other windings, although they are not resonant to that particular frequency. When all' the windings link the same magnetic circuit in series, the relatively powerful magnetic field established by ;a current of a certain frequency passing through its own particular winding acts inductively upon the other windings setting up counter-electromotive forcesin them which tend 'to prevent -the gassage of currents of that same frequency.

y arranging the primary windings to link separate magnetic circuits or separate parts of the same magnetic circuit, this mutual.

inductive effect is reduced, since the counter electromotive force opposing the passage of current through any winding is dependent.

upon only the magnetic field established b that winding itself, while in the case in which the windings all link the same magnetic circuit, the counter-electromotive force opposing the passage of current is dependent u on the sum of the magnetic fields establis ed by all the windings. The counter-electromotive force generated by the varying magnetic field is neutralized in the latter case by the condenser in the circuit tuned to that particular frequency; but in the other circuits it is only partly neutralized and its valud should be, therefore, kept as low as possible; This arrangement of resonant circuits, by increas ing the flow of current set up through agiven set of windings by a given available prim electromotive force increases the total vanable field strength and provides for more eflicient operation, since the magnetic fields are combined at the point of application,-

the movable armature, or the diaphragm.

It is usually sufiicient to separate the parts of the magnetic circuit which bear the primary windings, although more complete separa-.-

tion may be provided in order to prevent mu-' tual inductive action due the leakage tween the various magnetic circuits. -Th1s arrangement of the magnetic circuits may be applied to any type of repeater employinga variable magnetic field; but it is more espe-.

cially advantageous in the case of the dynamo t pe, where it. is not necessary to concentrate the magnetic field over a small area' at the place of ap lication, as for example, on a diaphragm. he mechanical arrangement of the wmdin will vary with the type and the form of t e repeater, as will be understood by all skilled in this art.

In Fig. 2 the-windings of the several resonant 'circuits are linked around the yoke of the field magnet 't between the pole-pieces of which is-rotatably mounted the armature j provided with a commutator 7c upon which press the brushes 1, m, connected in any suitable wa onda ines. It will be understood by all skille in this art that the arrangement shown in Fig. 2 of the drawing'is merely diaammatic and is intended merely to illustrate the application of the resonant circuits of Fig. 1. to a repeater of the commutating dynamo type; and that the magnetic circuit or the secondary elements of the re eater .may be modifiedin any way desire prowith the receiver 2, as by the secvided such modification does not interfere the application of the system of resonant primary circuits to a repeater of the variable resistance 'ty and here, as in Fig. 2, the primary win ings link a common magnetic circuit. In this type of repeater the'variable magnetic field acts (directly or indirectl it may be) to vary the resistance of e ceases cuit (not shown).

In Fig. 4 there is shown an arrangeitnent comprising primary windings Which linlr arate magnetic circuits for the purpose here inbefore described. The primary windings.

- a, b are in circuit, respectively with the con densei's d, e, the elements of each circuit being so proportioned that each circuit is tuned to a certain fre uency, as hereiubeiore set forth. The win ing a links the magnetic circuit q, r, s,,while the winding 1) links the magnetic circuit 15, 'r, .9. While the field structure is shown as designed for the "dy" namo type of repeater, it will be understood that its form may be varied for use with the variable resistance type of re eater, an on ample'of which is shown in *ig. 3. In the arrangement shown. in Fig. 4, the current passing through either winding is not opposed by the countenelectrcmotive forces generated by the variable fields established y the other windings, except for the mag net-ic leakage which may exist between the circuits. The variable magnetic fields established by the variouswindings are cumulative .in their effect upon the secondary eleinent. v

It will be understood that I am not limited to the use of two separate magnetic circuits type of repeater.

it will be seen that the arrangement to emphasize the higher harmonic,

n a resonant circuit/the impedance of the windings dominates in opposing currents above the critical frequency. Below the critical frequency, the impedance of the condenser dominates. As the separation or" the magnetic circuits described reduces the etl'ect of the inductive impedance of the windings,

mission, which is desirable for the reason hefore stated.

. It will be understood that where, a current reinforcing device is herein referred to, a device which relays or reinforces the electrical ,brought to bear upon. a dynamo armature, transmitter diaphragm or similar device.

What I claim is:

l. The combination with a source of current having diverse frequencies, of a plurality of inductive windings in circuit there with; a condenser for each of said windings, each condenser and its cooperating winding being proportioned for resonance to a given frequency from said source; separate magnetic circuits each of which is linked by one of said windin s and a currentreinforcing device control ed'by the variable magnetic field established. through said. magnetic circuits.

2. The combination with a source of current having diverse frequencies, of a pluralitv of primary circuits connected therewith, eac circuit being resonant to a given frequency from said. source; a magnetic field ener ized by said current; and an. armature which ro tates in said field.

The combination. with a source of urrent having diverse frequencies, of a plura ity of primary circuits connected therewith, each circuit being resonant to a given frequency from said source a plurality of separate magnetic circuits each of which is linked by one of said primary circuits; and a secondary circuit in inductive relation to said circuits.

4. The combination with a source of cur-,

rent having diverse frequencies, of a plurality of primary circuits connected therewith, each circuit being resonant to a given frequency from said. source; and a movable secondary element in inductive relation. to said primary circuits. l

5. The combination with a source of cur rent having diverse frequencies, 0 a pluralit of primary circuits connected therewith, eac circuit being resonant to a given frequency from said source; a plurality of separate magnetic circuits each oi which is linked by one of said primary circuits; and a movable secondary element in inductive relation to said primary circuits.

6. The combination with a source of cur-' renthaving diverse Frequencies, of plurality of inductive wmdings connected t ierewitli and in iiarallol with each other a condenser mounted in series with each oi said windings, each condenser and its cooperating winding" being proportioned for resonance to a given frequency from. said source; a plurality of separate magnetic circuits each of which is linked by one of said windings and a currentreinforcing device controlled by the variable magnetic lield established through said magnetic circuits.

7. In combination, a plurality of circuits eachcontaining an inductive winding and a condenser, said winding and condenser being proportioned for resonance to a, given fre- In testimony whereof I hereunto set my quency; s source of current having diverse hand this sixth day of July, 1906, at said frequencies connected with said circuits; a Chicago, in the resence of two witnesses. magnetic field energized by said current; en ULIAN A. STRATTON.

E, armature in said field; and a secondary c1r- Witnesses:

curt the current in which s controlled by said HERMAN E. BAIR, armature. l HARRY T. REYNOLDS. 

